In regards to the Castlevanias that were Metroidvania style, I'm partial to Harmony of Dissonance myself. 
I'm also a huge fan of Harmony of Dissonance.
Harmony of Dissonance seems to get a lot of crap, but it’s a fun game. The graphics and music get most of that criticism, mainly from people who don’t understand the situation. Circle of the Moon received a lot of complaints for how dark the screen was on the original non-backlit GBA, so the graphics were made brighter and more colorful in the follow-up, which showed up better but didn’t really fit the spooky aesthetic. And correct me if I’m wrong, but I read the low quality of the music was because the programmers literally ran out of allotted memory and had to reduce the quality to fit it all in.
Anyway, it’s a good example of gameplay trumping any visual or aural deficiencies.
Not the best metroidvania but I do have a soft spot for that game
First metroid vania game that I have played Didn't really know about the castlevania series beforehand. came in a random set and it looked weird.
Friends said it looked like a trash game they weren't really that knowledgebale with retro games when it's not the popular stuff such as mario zelda. neither was I.
so I didn't try it out until a store said they would give me 30$ for a lose cardridge in an era when gba deals where cheap and plentyfull. So I kept it and checked it out. also triggered me to collect for other consoles such as ps1 ps2 since castlevania games existed on that console aswell in wich I discovered allot of other games that I liked.
Considering the prices nowadays I'm not to sure if I would ever consider trying the castlevania series if I started from scratch today since I would probably just stick with the mainstream and some titles from the past I would just neglect it's existence. I doubt I would have come across a castlevania title randomly in the current era. Maybe I'd play hollow knight and know of castlevania afterwards since that game at the very least has become a bit popular.
That aside
The music was still great I'd say and the grapics where most definitely a huge step up from the moon circlet and way above average for gba standards. grapics wise it still had a spooky astetic at times and when it was to colorfull I'd say it definitely has an underworld/hell theming wich defenitely fits the series pretty well.
